-The first input after a blocked jump-in is often dropped
This is not a bug, this is bound to the combo system of the game
Basically you can't do a link from a character's attack to another, no matter how much hit stun you have
If you want to do a combo, you have to "link" your moves only by canceling each moves to another, and it will combo if the hitstun is long enough
So, how do you combo from a jump in ?
You have to cancel the recovery frame of your jump in attack to another attack, so that the "link" will happend, but it's not a link, it's a cancel
If you input it too late, no matter how huge the hitstun of a jump in attack is (and it really is huge), you will not be able to combo anything
You can feel the huge recovery of a jump in attack by whiffing one and trying to jump again, but this recovery isn't there when you do a proper link after a jump in
This allow for huge whiff punish if you whiff your jump in attack, since you can't cancel the recover on whiff
So you have to input the follow up of your jump in very early in the jump, like, when you are still in the air. Chris G talk about this quickly in the very long video he did on twitch when the game was released, he didn't explain it in depth though
Note : you can't cancel the recover of a jump in attack with a b3 or a f3, try it, it just throw out a neutral 3
What does it mean in a summary ?
-You have to input the follow up very early in the jump in order to combo
-You can't option select on a jump in because of this huge recover, no auto-anti backdash, no guard on fast wake up attack
-This explain why some chain combo still combo even if some hit whiff in between, since it still some attack canceling each other
-You can use a huge hitstun, from a jump in attack or any attack with a huge hitstun, to throw out a guaranted high attack, your opponent have to block it, or eat it, but can't duck it since all hitstun are force stand. This is what happend when your first hit drop after a jump in
Note that some hitstun don't follow this rule, like Batman's trait or his MB df1
So they could switch jump in attack's histun to a hitstun more like these one, but I think they did it on purpose to avoid option select